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I am using accelerometer MMA766 to read values. Used the following commands

root@raspberrypi:/home/pi# i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- 4c -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@raspberrypi:/home/pi# i2cdump -y 1 0x4c b
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
root@raspberrypi:/home/pi#

Why I couldn't read any values?

UPDATE:

I followed the instructions in this link. What I used to connect is

  • Connect VCC to the first pin on the front row (near label P1)
  • Connect SDA to the second pin on the front row
  • Connect SCL to the third pin on the front row
  • Connect GND to the fifth pin on the front row
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2
  • 2
    Could you please give more information. How is it connected, what did you use, drivers, etc. Anything constructive. This is a very hard question to answer, without anymore details, the possibilities are endless.
    – Impulss
    Jan 22, 2013 at 6:17
  • Have you had any success with I2C with any thing else? Maybe you still have a wiring issue or driver issue.
    – Piotr Kula
    Jan 22, 2013 at 10:18

1 Answer 1

Reset to default
2

What were you actually expecting as output from the 

i2cdump

command? That nearly only works well for memory chips and I guess RTCs, or chips that without any request output something (Temperature Sensors, some not all of them).

This IC needs some stimulation in the form of some settings before it outputs something usefull. I assume you're talking about the Freescale MMA7660FC (There is also a Bosch component that is called MMA766, but that dissipates 15W so, I don't think we're talking about that):

According to the datasheet, it has a couple of modes of operation (page 9), it needs to have power supplied to the DVDD AND the AVDD pins before it will even start to think about doing something. (It will otherwise be in Power Down mode or Standby mode).

If you did not read this datasheet yet, I urge you to read it, it contains a lot of information about how to use this chip, and how to set the configuration to make it do what you want.

And please confirm that we're talking about the same chip, because otherwise it is very difficult to help you.

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